This invention relates to a tool for measuring the ride height of a vehicle. In particular, it relates to a tool having a support member and two measurement members for determining whether a measured ride height of a vehicle is within a tolerance range for a specified ride height.
A ride height for a vehicle or trailer is typically defined as a vertical distance between a wheel""s axis of rotation and the bottom of the frame rail at the centerline of the vehicle/trailer suspension. The centerline of the suspension varies per design. For example, the centerline of the suspension on a dual or tandem axle design is usually half-way between the two tandem axles. Whereas, the centerline of the suspension of a single axle design is longitudinally aligned with the wheel""s axis of rotation.
Truck manufacturing is one example of a time when the ride height needs to be measured and adjusted. A truck manufacturer must typically measure and adjust the ride height of a newly built truck on the production line to meet the design specifications. In the past, the truck manufacturer typically made such measurements by having a technician or engineer crawl under the newly built truck and manually measure the vertical distance between the bottom of the frame rail and the bottom of the air spring (which is at a known distance with respect to an axis of rotation) using a tape measure. The actual ride height was then calculated from the frame rail-to-air spring distance. This actual ride height was then compared to the manufacturer""s design to see if it was within the specified range of tolerance. If the ride height was outside the specified range, then the ride height was adjusted, and the manual measurement was repeated after each ride height adjustment. This process was repeated until the ride height was within the manufacturer""s design range.
This method of measuring the ride height is cumbersome, time consuming, and prone to errors for a number of reasons. First, using a tape measure to gauge the vertical distance is inherently inaccurate because often such vertical distance is between two points that are not along a mutual vertical axis. For instance, on a tandem axle truck the centerline of the rear suspension is often not longitudinally aligned with the air spring. Thus any rake or tilt in the frame rail can create inaccuracies in the measurement. Also, measurements taken from a graduated scale having standard inch or metric increments, such as a typical tape measure, are slow and tedious to repeatedly read and subject to human error upon repeated use. Secondly, the measurement between the bottom of the frame rail and the bottom of the air spring used in the past by truck manufacturers may not be the true ride height measurement per the design. The reason for the variance is that often the builder or assembler must shim the axle during assembly. Hence, the spatial relationship between the frame rail, air spring, and wheel axle may vary depending on the size and number of shims needed during assembly. Thirdly, this method of measuring ride height does not make the application of measurement tolerance ranges convenient.
Another instance when the ride height may need to be measured and adjusted is when installing or repairing a vehicle suspension having an adjustable ride height, such as an air spring suspension on a heavy truck. When installing or repairing a vehicle suspension having an adjustable ride height, it is often necessary to measure and adjust the ride height to ensure that the suspension has a ride height that is within the tolerance specified by the manufacturer.
The proper ride height and elimination of frame rake or tilt are especially important on tandem axle vehicles because deviation from the design ride height can generate excessive vibrations in the drivetrain. Such vibrations in the drivetrain often cause damage to various drivetrain components, such as transmission synchronizers. Therefore, to improve the production quality and reliability of vehicles manufactured having adjustable suspensions, such as the truck manufacturing example above, there is a need for a tool, as well as a method of using such tool, to enable a more accurate and convenient measurement of ride height. Such a tool and method will enable an assembler or builder, as well as repair persons, to more efficiently build or rebuild a suspension within the proper design tolerances and specifications. Also, there is a need for a less time consuming way to measure the ride height. Furthermore, there is a need for a tool for measuring ride height that provides a tolerance range for the measurement.
Many of the needs outlined above are addressed by the present invention. It is an object of the present invention to provide a tool and method for using such tool for accurately measuring the ride height of a vehicle without facilitating human errors when reading the measurement.
Another object of the present invention is to provide a tool and method for using such tool for measuring a ride height of a vehicle easier and faster than prior tools/methods.
Yet another object of the present invention is to provide a tool and method for using such tool for measuring a ride height of a vehicle while adjusting the suspension of the vehicle without removing the tool from its measuring position.
Still another object of the present invention is to provide a tool and method for using such tool for measuring a ride height of a vehicle within a specified tolerance range.
In accordance with one aspect of the present invention, a tool is provided for indicating whether a measured ride height of a vehicle is within a tolerance range for a specified ride height. The measured ride height is equal to a vertical distance between a reference surface of the vehicle, such as a vehicle frame rail at a suspension centerline, and a rotational axis of a vehicle wheel. The tool comprises a support member, a first measurement member, and a second measurement member. The support member is adapted to extend vertically upwards from a generally horizontal reference surface. The first measurement member has a slidable relationship with respect to the support member to allow relative vertical movement therebetween. The first measurement member has a first reference mark defined thereon. The second measurement member has a slidable relationship with respect to the support member also to allow relative vertical movement therebetween. The second measurement member has a second reference mark defined thereon and an upper end. The second reference mark has a position selected to substantially align with the first reference mark when a vertical distance between the upper end of the second measurement member and the first reference mark corresponds to the specified ride height. The tool may also include a range indicator to define a tolerance range for the specified ride height.
In accordance with another aspect of the present invention, a tool is provided for measuring a ride height of a vehicle. The tool comprises a support member, a first measurement member, and a second measurement member with a graduated scale thereon. The support member is adapted to extend vertically upwards from a generally horizontal reference surface. The first measurement member is releasably attached to the support member so as to be vertically repositionable along the support member. The first measurement member has a first reference mark defined thereon. The second measurement member has a slidable relationship with respect to the support member to allow relative vertical movement therebetween. The second measurement member has the graduated scale defined thereon and an upper end. The first reference mark aligns with a vertical position on the graduated scale to indicate a measurement of the ride height when the upper end is vertically aligned with the reference surface of the vehicle.
In accordance with yet another aspect of the present invention, a tool is provided for indicating whether a measured ride height of a vehicle meets a predetermined ride height. The tool comprises a support member, a first measurement member, and a second measurement member. The support member is adapted to extend vertically upwards from a generally horizontal reference surface. The first measurement member is movably fixed relative to the support member, and it has a first reference mark defined thereon. The second measurement member has a slidable relationship with respect to the support member to allow relative vertical movement therebetween. Also, the second measurement member has a slidable relationship with respect to the first measurement member to allow relative vertical movement therebetween. The second measurement member has a second reference mark defined thereon and an upper end. The second reference mark has a position selected to substantially align with the first reference mark when a vertical distance between the upper end of the second measurement member and the first reference mark corresponds to the specified ride height.
In accordance with yet another aspect of the present invention, a method of using the tool to indicate the ride height of a vehicle and a method of adjusting a vehicle ride height while checking the ride height measurement are provided.